The present invention relates to a vehicle antitheft technology.
As a vehicle antitheft measure, an immobilizer has been adopted to verify a unique ID code. The immobilizer is an antitheft technology of disabling an engine from starting unless a predetermined condition is satisfied. However, an instrument holding the immobilizer is sometimes illicitly replaced so that the vehicle is stolen for an illegal purpose. JP-A-H11-182389 discloses, as a countermeasure, that an engine control unit disables an engine start by determining replacement of a remote engine starter. Combination of other instruments or multiplex communication with the immobilizer enhances antitheft performance. In JP-B2-P3137443, a plurality of control units composes antitheft guard structure through multiplex communication, which thus realizes a large-scale alarm system.
Additionally, in JP-A-P2001-14575A, detection of vehicle abnormality leads to informing a driver of the effect and also detection of an unauthorized operation against the vehicle leads to deterring or ceasing a vehicle control function by a remote operation.
However, even if the above countermeasures are adopted, unauthorized replacement of a control unit or replacement to a remodeled unit disabling the immobilizer permits the vehicle to recover inherent performance. Even an authorized user is thereby able to operate the vehicle as usual. Moreover, when the vehicle is conveyed by a wrecker capable of generating radio noise or shielding radio wave, the alarm system to the outside of the vehicle is intercepted. After the steal, removal or remodeling of the control unit can break down the alarm system of the stolen vehicle. The stolen vehicle is thus used illicitly while maintaining the inherent vehicle function.
Altogether, the conventional antitheft measures turn out to be useless with the replacement of the immobilizer itself or the engine control unit detecting the replacement of the immobilizer. The alarm system to the outside of the vehicle or the remote operation instrument is also become ineffective by interruption of the alarm transmission or the replacement of the instrument itself.
It is therefore an object of the present invention to provide an effective vehicle antitheft technology.
To achieve the object, all or part of performance of a network system is disabled or reduced by determining a hazard state where a vehicle theft possibly arises. This approach is very different from a conventional antitheft measure which mainly focuses on an alarm or prevention of the steal such as an alarm to the outside of the vehicle or disabling of an engine start. The invention concentrates on reducing vehicle performance when a stealer tries to disable the antitheft measure or the theft alarm, which approach dispirits the stealer""s mind aiming at the vehicle steal. Here, the vehicle is assumed to be provided with an in-vehicle network system where a plurality of electronic control units is connected with the network. A luxury car is typically equipped with a massive and complicated structure of the network while the luxury car is in many cases aimed at by the stealer. In the network system, data among electronic control units are frequently communicated so that disabling or reducing of all or part of the network system results in extreme reduction of the vehicle performance.
In another embodiment of the invention, vehicle performance remains disabled or reduced as a default state until verification of the user is successfully completed through a predetermined process. This approach is effective in preventing the vehicle steal from occurring.